We propose to study, using techniques of somatic cell genetics, (1) human genetics and (2) virus-cell interactions. We will develop and use a number of selective systems involving purine and pyrimidine pathways for the chromosomal assignment and regional gene mapping of both human and mouse genes, Clone panels of human-rodent hybrids will be constructed for the purpose for mapping unselected genes. Furthermore we will utilize these selective systems and human fibroblasts with X/autosome translocations to study SV40 integration into human chromosomes. Gene transfermediated by herpes simplex virus will be explored with regard to potential integration of the herpes viral genome into host chromosome(s).